1. Field
A method of patterning a block copolymer layer and a patterned structure are disclosed.
2. Description of the Related Art
Recently, in view of a decrease in a size of electronic devices and an increase in an integration degree of semiconductor devices, a demand for lithography technology for forming a fine nano-sized pattern for fabricating a semiconductor memory or a logic circuit has increased. Typically, conventional photolithography technologies suffer from difficulties in realizing a nano-sized fine pattern, in particular, a nano-pattern of less than or equal to about 20 nm, due to the wavelength resolution limit. Accordingly, various methods based on new principles of fabricating nano-sized patterns have been researched. One of these methods utilizes a self-assembled nano-structure.
A block copolymer is a type of a polymeric material that may be self-assembled to form a nano-structure. The molecular structure of the block copolymer typically includes chemically different polymer blocks connected to one another through a covalent bond. Such polymer blocks may be self-assembled to form various repeating nano-sized structures such as a sphere, a cylinder, and a lamella with a period of about 5 to about 50 nm. The resulting nano-structures are usually thermodynamically stable, and in the process of synthesizing the block copolymer, the size and properties of the nanostructure may be controlled, for example, via changing the monomer types, the ratio between the monomers, and a molecular weight of the polymer. Vertical lamella or horizontal cylinder structures prepared from a block copolymer film may become directed self-assembled structures via chemical epitaxy or graphoepitaxy. In the process of directed self-assembly of the block copolymer, the orientation or the direction of the lamella or cylinder structures may be controlled by adjusting the surface energy of the underlying substrate. Selectively etching/removing a certain type of blocks in the block copolymers from such structures enables the formation of a desired pattern, which may be used in the next generation lithography. Thus, there remains a need for a specific patterning method utilizing a directed self-assembly of a block polymer.